Devices are known for wrapping or securing items for handling, transport and the like. Often, multiple items are placed together, bundled and a shrink wrap material is positioned around the items. The shrink wrap material is then heated to shrink around the bundled load. Such shrink wrap maintains the stability of the load and can provide protection against environmental conditions, such as water, dirt and the like.
Heating the shrink wrapped load is often carried out in a shrink wrap tunnel. Typically, a load to be shrink wrapped is presented to the tunnel on a conveyor. The load is wrapped with the material, which shrinks when subjected to heat. The load is conveyed through the tunnel and as it moves through the tunnel, heat, typically applied by forced air heaters, is blown over the wrapped load. The heat is sufficient to shrink the wrap onto the load to create a tightly wrapped package.
Known shrink wrap tunnels, include stationary walls. Because the heating elements are mounted to the walls, they too are stationary relative to the load moving through the tunnel, regardless of the size, or width of the load.
Loads, however, can consist of a wide variety of items, materials and the like, of a likewise wide variety of sizes. As such, there can be significant inefficiencies in heat shrink tunnels, especially when, for example, a narrow load is conveyed through a relatively wide tunnel. That is, the tunnel may be quite large, and the load much smaller. Thus, there are thermal losses and inefficiencies due to convective losses.
Accordingly, there is a need for a shrink wrap tunnel that reduces the inefficiencies inherent in the shrink wrapping process. Desirably, such a shrink wrap tunnel has a width that can be varied to accommodate loads having a variety of widths. More desirably, in such a shrink wrap tunnel, hot air can be directed or forced into open spaces around a wrapped load and drawn from the wrapped load, to minimize heat losses.